This invention relates to tuftable fabrics and tufted products and, more particularly, primary carpet backings and tufted carpets.
Most backings for carpets are fabrics woven from synthetic yarns. While many fabric constructions, yarn configurations and compositions have been used or described in published sources, woven polypropylene tape fabrics are preferred primary backings due to desirable properties that include tuftability, strength, mold resistance and cost.
For some applications, however, conventional backings have limitations. For example, although nonwoven polyester backings are typically more expensive than woven tape primary backings, polyester nonwovens are often favored for fine and intricate patterned, tufted broadloom carpets because even minor irregularities in the weave of woven backings can lead to pattern nonuniformity and mismatches when the backings are tufted. With growing emphasis on style and design in pattern-tufted carpets, demands on backings for regularity and stability will increase.
In woven primary backings, irregularities typically take the form of various deviations from weftline straightness. One such deviation, commonly referred to as xe2x80x9cbow,xe2x80x9d occurs when weft yarns are disposed in the shape of an arc, instead of straight, across the backing. Another, referred to as xe2x80x9cskew,xe2x80x9d occurs when weft yarns are not perpendicular to warp yarns but instead are diagonally offset or skewed across the fabric. When backings with bow or skew are tufted, misalignment of tufting needles with weft tapes may result and contribute to pattern distortion and mismatch. Random, isolated deviations from straightness in segments of a backing""s weftline, or xe2x80x9cblips,xe2x80x9d can also occur and extra thickness of fabrics in selvage areas can cause deviations known as xe2x80x9chooking.xe2x80x9d
For pattern-tufted broadloom carpets, resistance of both backings and tufted backings (also referred to as xe2x80x9cgreige goodsxe2x80x9d) to even small, in-plane deformations also is important for pattern uniformity. While traditional woven polypropylene tape backings have good resistance to deformations in the directions of their warpwise and weftwise axes, better stability of some nonwovens against off-axis deformations is an advantage when tufting fine and intricate patterns. With woven backings, shifting of the weave and nonuniform movement of backings as they advance through tufting can result in unacceptable bow, skew, other distortions, pattern mismatches and nonuniformity. When goods are not properly aligned during passage through finishing steps, such as dyeing, application and drying of backcoats, the tufted backings can skew if one side moves ahead of the other. Bow and skew can occur if greige goods experience different cross-machine direction tensions as they move through drying ovens, such as from dragging over rolls, nonuniform roll diameters, and roll misalignment. Irregularity also can result when greige goods are not stretched in the cross-machine direction sufficiently to maintain straightness of weft yarns.
It is known that needling, fusing or needling and fusing fibers or nonwoven fibrous webs or fabrics can improve dimensional stability and other properties of woven backings. The needled or fused fibers stabilize the weave against shifting. In addition, penetration of fibers through the weave as a result of needling and/or tufting can cause packing of fibers around tufts where they penetrate the backing, thereby contributing to stitch lock. The terms xe2x80x9ccalendar-lock weavexe2x80x9d and xe2x80x9cfiber-lock weavexe2x80x9d (xe2x80x9cCLWxe2x80x9d and xe2x80x9cFLWxe2x80x9d) are well known in the carpet backing industry as designations for composites with fibers or nonwoven webs fused to woven backings, or fibers needled to woven backings, respectively.
U.S. Pat. No. 3,605,666 describes FLW composites having a woven backing fabric needled with a web or batt of selected, garneted staple fibers to provide a backing surface that is dye-compatible with carpet face yarn. In tufted carpets, the nonwoven layer is disposed on the pile side and said to improve appearance by hiding the woven fabric and reducing light reflection. The woven fabric is preferably woven from polypropylene filaments and the nonwoven is described as a thin but dense material, with preferred staple fiber lengths of 1-4 inches. The patent does not attribute improved dimensional stability to the needled nonwoven web, stating instead that the woven fabric provides substantially all of it in the disclosed products.
U.S. Pat. No. 4,053,668 describes manufacture of carpets by tufting a woven tape fabric that has been needled with a layer of staple fibers deposited onto it. The composites are described as having improved dimensional stability as a result of yarns in the weave being held against relative sliding by the needled fibers. Carpets made from the backings are tufted so that the needled layer is disposed on the back side of the tufted structure. The woven fabric is a woven polypropylene scrim with ribbon filaments; a 30xc3x9711 construction of 45 mils wide, 2.2 mils thick warp tapes and 90 mils wide, 3.6 mils thick weft tapes and weighing 3.3 ounces per square yard (xe2x80x9cosyxe2x80x9d) is preferred. Nylon staple fibers are preferred for dye-compatibility with face yarns, with lengths of 1.5-3 inches, deniers of 15-20, and an application rate of 5.5 osy.
Another composite backing described as providing improved dimensional stability and, specifically, resistance to bow and skew for improved pattern definition in printed carpets, is found in U.S. Pat. No. 4,069,361. The backings have a woven primary backing fabric to which is needled a 0.5-3 osy batt of staple fibers, which are then fused to form an integrated composite structure. The fabric is woven from polypropylene tapes or filaments. The batt is composed of staple fibers that can be fused without fusing or adversely affecting the woven fabric. Staple fibers composed of polypropylene are specifically disclosed.
Improved dimensional stability of needlepunched nonwovens composed of polypropylene staple fiber and fused at least at one surface, and use of the nonwovens in carpet backings, are also known from Canadian Patent 1,185,844.
U.S. Pat. No. 4,123,577 describes CLW primary backings having a woven polypropylene tape fabric to which is fused a nonwoven fabric composed of dyable fibers in combination with heat fusible fibers. The backings are characterized by improved dimensional stability, including stability for fine gauge tufting, and dye-compatibility of the fused layer with face yarns. Fusing the nonwoven to the woven is said to result in backings with higher tensile strength than FLW composites because needling the composite is avoided. Woven polypropylene tape primary backings and nonwoven fabrics composed of blends of nylon and polypropylene fibers are disclosed. Nonwoven fabric weights are about 3-70 g/m2 (0.09-2 osy), with preferred weights as small as possible while providing desired dimensional stability and coverage to avoid grinning.
U.S. Pat. No. 4,140,071, noting difficulties with composites of woven backing fabrics needled with carded staple fiber webs of low basis weight, describes carpets made by tufting face yarn simultaneously through a woven polypropylene tape primary backing fabric and a bonded, lightweight nonwoven web of dyable continuous filaments. Improved tensile and tear strength are said to result from use of the bonded, continuous filament nonwoven, as compared to separate needling of the woven and nonwoven fabrics. Disclosed web weights are about 13-30 g/m2 (about 0.4-0.9 osy). Improved dimensional stability of finished carpets is also said to result from tufting simultaneously through a woven or nonwoven backing fabric, such as a conventional primary backing, and a stronger, less stretchable open weave backing fabric, such as conventional secondary backing, according to U.S. Pat. No. 5,962,101.
U.S. Pat. No. 4,242,394 describes a three-component primary backing, said to have excellent dimensional stability, in which a woven polypropylene tape primary backing fabric and a woven, extruded net or continuous filament nonwoven reinforcing layer are needled with a layer of 2xc2xd-3 inches long, 3-15 denier staple fibers. Staple fibers composed of polypropylene, polyester and nylon are disclosed.
Secondary carpet backings with needled woven and nonwoven fabrics also are known. While tuftability, strength and stability against deformation in tufting and finishing operations are features of importance for primary backings, penetrability and adhesiveness of binders such as latex formulations and stability against large strain deformations, such as those encountered in handling, installation and use of finished carpets, are more important in secondary backings. Thus, while primary backings are typically closed weave fabrics with tapes in both the warp and weft, secondary backings are more commonly open weave fabrics, frequently with spun or filament yarns instead of tapes in at least one of the warp and weft for better binder penetration and adhesion. Secondary backing fabric composites with needled fibers and nonwoven fabrics for improved stability, adhesion, and aesthetic properties are well known. Thus, U.S. Pat. No. 3,817,817 discloses composites with improved dimensional stability and hand in the form of woven polypropylene ribbon fabrics with needled staple fibers. The needled staple fibers form a layer on the backing surface that ultimately forms the bottom of finished carpets, with penetration of fibers through the backing also said to aid in preventing edge raveling and improving adhesion of binders. Polypropylene staple fiber lengths of 1xc2xd inches, deniers of 15, application weights of 1xc2xd-2 osy and needling at 234 needlepunches per square inch are preferred. A recent example is found in U.S. Pat. No. 6,060,145.
While composite backings having woven fabrics needled with, fused to, or needled with and fused to staple fibers and staple fiber or continuous filament nonwovens are well known as backings for tufted carpets and have been recognized for dimensional stability, resistance to bow and skew, improved tuft lock and other benefits, composites also have limitations. Those with staple fibers or nowoven webs needled or fused to woven backing fabrics tend to resist deformations better than their woven fabric components, but penetration of needles and face yarn during tufting tends to disrupt integrity of the nonwovens or fiber layers, thereby reducing the stability they impart. Thus, deformations due to tufting and variability in finishing still can cause pattern mismatches.
Tufting woven backings and nonwovens brought together at the tufter, instead of previously needled or fused into composites, avoids losses of stability due to prior needling but the separate fabrics can both be sources of irregularities and require added, more complex handling and control equipment to be integrated with tufting.
Fusion of fibers or nonwovens to woven primary backing fabrics avoids loss of strength and stability due to needling; however, fused resin agglomerates can cause tufting needle deflection and, in turn, pattern distortion. Fusing woven backings and fibers or nonwovens also requires that the latter include fibers composed wholly or partly of synthetic resins that melt at temperatures below those at which woven backings are damaged by heat exposure. Beyond costs of lower melting resins, their compatibility with other backing or carpet materials in terms of adhesion of carpet binders, processibility, and recyclability are concerns. Effects of different resin compositions on dye receptivity, light reflectance and other properties may be unpredictable and affect product quality.
Thus, there are needs for tufted carpets with improved pattern uniformity and tuftable backings with improved dimensional stability, and particularly stability against small in-plane deformations for intricate tufting, and retention of stability during and after tufting.
Briefly, this invention provides improved tuftable backing composites, tufted products and methods for their manufacture.
In one embodiment, the invention provides tuftable backing composites that comprise a tuftable closed-weave fabric comprising warp and weft tapes and having a coherent nonwoven web of staple fibers in contact with one surface of the fabric without fusion thereto and a plurality of fibers from the web penetrating the fabric to attach the web to the fabric, wherein the fibers have a weight of 1 to about 4 osy, the fibers of the web are oriented in at least two directions and a plurality of the fibers of the web are fused, and wherein weft tapes of the composite have weftline straightness suitable for patterned tufting and the composite has stability against deformation during tufting as indicated by machine-direction deformation resistance of at least about 20 pounds and off-axis deformation resistance of at least about 4 pounds/inch. Such composites tufted with or further comprising tufted face fibers are also provided.
In another embodiment, the invention provides a tufted product comprising a backing having face yarn penetrating therethrough to form a plurality of tufts on a face side and a plurality of stitches on a stitched side, wherein the backing comprises a closed-weave fabric comprising warp and weft tapes and a coherent nonwoven web of staple fibers on the stitched side and in contact with a surface of the fabric without fusion thereto and a plurality of fibers from the web penetrating the fabric, wherein the fibers have a weight of 1 to about 4 osy, the fibers in the web are oriented in at least two directions and a plurality of the fibers in the web are fused, and wherein the tufted product has machine direction deformation resistance of at least about 15 pounds and off-axis deformation resistance of at least about 2.5 pounds/inch.
Another embodiment of the invention provides a method for making a tuftable backing comprising needling to a tuftable, closed-weave fabric comprising warp and weft tapes a coherent nonwoven web comprising staple fibers oriented in at least two directions and a plurality of which are fused, wherein the web has a weight of 1 to about 4 osy and off-axis deformation resistance of at least about 2.5 pounds/inch and the needling is effective to affix the web to the fabric and stabilize the fabric.
In another embodiment, the invention provides a method for making a tufted product that comprises tufting face yarn into a first side of a tuftable backing composite comprising a tuftable, closed-weave fabric comprising warp and weft tapes and having a coherent nonwoven web of staple fibers in contact with a surface of the fabric on the first side without fusion thereto and a plurality of fibers from the web penetrating the fabric to attach the web to the fabric, wherein the fibers have a weight of 1 to about 4 osy, the fibers in the web are oriented in at least two directions and a plurality of the fibers in the web are fused, and wherein the weft tapes of the composite have weftline straightness suitable for patterned tufting and the composite has stability against deformation during tufting as indicated by machine direction deformation resistance of at least about 20 pounds and off-axis deformation resistance of at least about 4 pounds/inch.
For purposes hereof, the terms xe2x80x9cmachine direction,xe2x80x9d xe2x80x9ccross-machine directionxe2x80x9d, xe2x80x9cwarpxe2x80x9d and xe2x80x9cweftxe2x80x9d are used for their commonly accepted meanings. xe2x80x9cMachine directionxe2x80x9d refers to a direction corresponding to the direction of advancement through a process line while xe2x80x9ccross-machinexe2x80x9d, or simply xe2x80x9ccross,xe2x80x9d xe2x80x9cdirectionxe2x80x9d corresponds to a direction transverse to the machine direction. xe2x80x9cWarpxe2x80x9d tapes refer to tapes with lengths in the machine direction while xe2x80x9cweftxe2x80x9d tapes are tapes with lengths in the cross direction. The term xe2x80x9cmilsxe2x80x9d means onexe2x80x94one thousandth (0.001) of an inch. xe2x80x9cMachine direction deformation resistance,xe2x80x9d abbreviated xe2x80x9cMDR,xe2x80x9d refers to force, applied in the machine direction in the plane of a sample, such as a composite, fabric or tufted product, required to cause 5% elongation of the sample. xe2x80x9cOff-axis deformation resistance,xe2x80x9d abbreviated xe2x80x9cODR,xe2x80x9d refers to force, applied at a 45xc2x0 angle to the machine direction in the plane of a sample, required to cause 5% elongation of the sample. MDR and ODR are determined according to procedures described in detail immediately preceding the examples.